It is of paramount importance that a missile not undergo launch except when desired, and launch systems must be carefully designed to prevent the possibility of accidental launch. At the same time, a desired launch must not be delayed by any time-consuming procedures for releasing preventive lock mechanisms. Hence, it is desirable that an electrical locking system be used which may be rapidly disengaged at launch, but which may not be accidentally disengaged at other times due to accident, system malfunction or extraneous electrical power. A locking mechanism which could be disengaged merely by supplying electrical power to the mechanism would be subject to an unacceptable degree of likelihood of accidental disengagement. On the other hand, a system requiring a predetermined sequence of electrical pulses would have a very low probability of accidental disengagement, particularly where the electrical pulses are sequenced via a module which may be loaded into the system just prior to launch.